Onclick Change Iframe

HTML

<button id="myButton">Click</button>

<br>
    
<iframe id="myFrame" src="#" border="0"></iframe>

CSS

iframe {
    border: none;
    width: 100%;
    height: 100%;
    min-height: 400px;
}

JavaScript

var mySites =  [
    "http://placekitten.com/g/400/350",
    "https://isitchristmas.com/",
    "http://www.boohbah.tv/zone.html"
    ];

var count = 0;

document.getElementById('myButton').onclick = function() {
     
    var myFrame = document.getElementById("myFrame");
    
    myFrame.src = mySites[count];
    
    count++;
    
    if(count > 2) {
         count = 0;   
    }
    
}